The present invention relates to an uninterruptible power supply unit which has a battery, and which normally supplies an electric power of an AC power source to a backed-up apparatus, and, when the AC power source is interrupted, supplies an electric power from the battery to the backed-up apparatus.
FIG. 4 is a view showing the configuration of a conventional uninterruptible power supply unit. In the figure, 40 denotes an AC power source, 41a denotes an uninterruptible power supply unit, and 42 denotes a backed-up apparatus such as a computer system which, when the AC power source 40 is interrupted, is to be backed up by the uninterruptible power supply unit 41a. Furthermore, 50 denotes a battery which is incorporated in the uninterruptible power supply unit 41a, 51 denotes a charge and discharge circuit which, when the AC power source 40 is in the normal state, causes the battery 50 to be charged by the AC power source 40, and which, when the AC power source 40 is in an abnormal state such as power interruption or momentary power interruption, causes the battery 50 to be discharged, thereby supplying an electric power to the backed-up apparatus 42, and 52 denotes a connector trough which the battery 50 and the charge and discharge circuit 51 are connected to each other. Furthermore, 53a denotes a case of the uninterruptible power supply unit 41a housing the battery 50, 54 denotes an opening which is used for replacement of the battery 50, 55a denotes a cover for closing the opening 54, 56 denotes a cover-opening detecting device which detects an opened/closed state of the cover 55a by using an optical switch or the like, and 57 denotes a charge and discharge circuit disconnecting switch which disconnects the charge and discharge circuit 52 from the AC power source 40.
When the AC power source 40 is normal, the uninterruptible power supply unit 41a supplies an electric power from the AC power source 40 to the backed-up apparatus 42, and closes the charge and discharge circuit disconnecting switch 57 to connect the AC power source 40 to the charge and discharge circuit 51 to charge the battery 50. When the AC power source 40 is in an abnormal state such as power interruption or momentary power interruption, the uninterruptible power supply unit 41a serves as a backup power source to discharge the battery 50 to supply an electric power to the backed-up apparatus 42. The battery 50 is repeatedly rechargable, but its power suppliable time is shortened as a result of aging. Therefore, the battery is usually replaced with a fresh one at two- or three-year intervals.
The uninterruptible power supply unit 41a detects the opened/closed state of the cover 55a by means of the cover-opening detecting device 56. When the cover 55a is opened, the unit judges that replacement of the battery 50 is to be performed, and then opens the charge and discharge circuit disconnecting switch 57 to disconnect the charge and discharge circuit 51 from the AC power source 40. As a result, it is possible to prevent replacement of the battery 50 from being performed during a charging process in which a charging current flows through the battery 50.
FIG. 5 is a view showing the configuration of a conventional uninterruptible power supply unit. A battery which is to be separately placed is additionally disposed. In the figure, 40, 42, 50 to 52, 54, and 57 denote the identical components as those of FIG. 4, and their description is omitted. Furthermore, 41b denotes an uninterruptible power supply unit, 53b denotes a case of the uninterruptible power supply unit 41b housing the battery 50, 55b denotes a cover for closing the opening 54, 58 denotes a battery replacement instruction switch which closes and opens the charge and discharge circuit disconnecting switch 57, 60 denotes a battery unit which is placed separately from the uninterruptible power supply unit 41b, 61 denotes an auxiliary battery which is incorporated in the battery unit 60, and which is connected in parallel to the battery 50, and 62 denotes a connector to which the auxiliary battery 61 is connected.
The uninterruptible power supply unit 41a of FIG. 4 is an example in which only the battery 50 incorporated in the uninterruptible power supply unit 41a is used as a battery. The uninterruptible power supply unit 41b of FIG. 5 is an example in which, in order to prolong the backup time, the battery unit 60 in which the auxiliary battery 61 is incorporated is additionally disposed so that a battery is configured by the battery 50 and the auxiliary battery 61.
When the AC power source 40 is normal, the uninterruptible power supply unit 41b supplies an electric power from the AC power source 40 to the backed-up apparatus 42, and closes the charge and discharge circuit disconnecting switch 57 to connect the AC power source 40 to the charge and discharge circuit 51 to charge the batteries (the battery 50 and the auxiliary battery 61). When the AC power source 40 is in an abnormal state such as power interruption or momentary power interruption, the uninterruptible power supply unit 41b serves as a backup power source to discharge the batteries (the battery 50 and the auxiliary battery 61) to supply an electric power to the backed-up apparatus 42.
In replacement of the batteries (the battery 50 and the auxiliary battery 61) in the uninterruptible power supply unit 41b, when the battery 50 incorporated in the uninterruptible power supply unit 41b is to be replaced, the cover 55b is opened. By contrast, when the auxiliary battery 61 incorporated in the battery unit 60 which is placed separately from the uninterruptible power supply unit 41b is to be replaced, the cover 55b is not opened. Therefore, the battery replacement instruction switch 58 is disposed so that, when the batteries (the battery 50 and the auxiliary battery 61) are to be replaced, the battery replacement instruction switch 58 is operated. When the battery replacement instruction switch 58 is operated, it is judged that instructions for the battery replacement has been given, and the charge and discharge circuit disconnecting switch 57 is then opened to disconnect the charge and discharge circuit 51 from the AC power source 40.
In replacement of the battery of the uninterruptible power supply unit, as described above, the charge and discharge circuit disconnecting switch 57 is opened in response to an operation of the cover-opening detecting device 56 or the battery replacement instruction switch 58, so that the battery replacement is prevented from being performed during a charging process. However, there is a problem in that, when power interruption or momentary power interruption occurs during a process of replacing the battery, it is impossible to exert the original function of an uninterruptible power supply unit that, in the case of power interruption, the unit supplies an electric power to a backed-up apparatus.
The invention has been conducted in order to solve the above-discussed problem. It is an object of the invention to obtain an uninterruptible power supply unit which, even when power interruption or momentary power interruption occurs during a process of replacing a battery, can supply an electric power to a backed-up apparatus.
The uninterruptible power supply unit of the invention is an uninterruptible power supply unit which has a battery and a charge and discharge circuit, and in which, when an AC power source is in a normal state, the AC power source is used as a power source to supply an electric power to a backed-up apparatus, and the battery is charged by the charge and discharge circuit, and, when the AC power source is in an abnormal state such as power interruption, the battery is discharged by the charge and discharge circuit to supply an electric power to the backed-up apparatus, wherein the battery is configured by a first battery and a second battery, the unit comprises: a first switch which connects the charge and discharge circuit to the first battery; a second switch which connects the charge and discharge circuit to the second battery; a first cover which is opened when the first battery is to be replaced; a second cover which is opened when the second battery is to be replaced; a first cover-opening detecting device which detects an opened state of the first cover; a second cover-opening detecting device which detects an opened state of the second cover; and a control circuit which controls opening/closing of the first switch and the second switch in accordance with opened/closed states of the first cover and the second cover, when the first cover is opened, the first switch is opened to enable replacement of the first battery, and, when the second cover is opened, the second switch is opened to enable replacement of the second battery.
Furthermore, the second battery, the second cover, the second cover-opening detecting device, and the second switch constitute a battery unit which can be disposed separately from the uninterruptible power supply unit, and which is connected to the charge and discharge circuit through a connector.
Moreover, the uninterruptible power supply unit has at least one of a display device and an alarm device, and, when the first cover or the second cover is opened, the control circuit gives an alarm for an opened state of the cover.
Furthermore, the first cover or the second cover comprises interlocking means, and the control circuit interlocks the second cover when the first cover is opened, and interlocks the first cover when the second cover is opened.